KR100875409B1 - Flame Retardant Expanded Polystyrene Foam Composition - Google Patents

Abstract

Expanded polystyrene foam compositions having flame retardancy, flame retardant expanded polystyrene foams, methods of making the foams, and products comprising the compositions and foams are provided. The flame retarded expanded polystyrene foam contains a flame retardant compound having the following structure (I):

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Description

Flame retardant expanded polystyrene foam composition {FLAME RETARDANT EXPANDED POLYSTYRENE FOAM COMPOSITIONS}

The present invention relates to flame retardant compositions and expanded polystyrene foams formed therefrom.

Styrene polymer compositions and foams such as expandable polystyrene foams are widely used in the manufacture of molded articles, paints, film coatings, and sundries. Typically, expandable styrene-based polymers, such as expanded polystyrene, are prepared by suspension polymerization of a mixture of styrene monomer (s) and flame retardant in water to form styrene-based polymer beads. Large blocks (eg, up to several meters in height) that are pre-expanded with steam and remolded with steam to form small beads (eg, on average about 1 mm in diameter) and cut to desired dimensions And 2-3 meters in width).

For some product applications, it may be desirable to reduce the flammability of such compositions and foams. Flame retardants for use in expanded polystyrene foams require several requirements including thermal stability, significant solubility in styrene, and high flame retardancy.

Halogenated flame retardant compounds have been proposed for use in various polymers. For example, US Pat. No. 3,784,509, each of which is incorporated by reference in its entirety; 3,868,388; 3,868,388; 3,903,109; 3,903,109; 3,915,930; And 3,953,397. However, some flame retardant compositions are not sufficiently soluble in styrene, which may adversely affect the formation and quality of polystyrene foam. If the insoluble particles act as nucleation sites, possible suspension failures may occur that result in a sudden increase in viscosity of the styrene / water mixture and rapid formation of large polystyrene masses in the reactor.

Accordingly, there is a need for flame retardant compounds for use in expanded polystyrene foams that are sufficiently soluble in styrene and will not interfere with the formation of foams.

Summary of the Invention

The present invention relates generally to flame retarded expanded polystyrene foam. According to one aspect of the invention, the expanded polystyrene foam contains a flame retardant compound having the structure:

The flame retardant compound may be present in an amount from about 0.1 to about 10 weight percent of the foam. In one aspect, the flame retardant compound is present in an amount from about 0.5 to about 7 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount from about 0.7 to about 5 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount from about 1 to about 2 weight percent of the foam.

The flame retardant may have a solubility in styrene of about 0.5% to about 8% at about 25 ° C. In one aspect, the flame retardant has a solubility in styrene of about 0.5% to about 10% by weight at about 40 ° C.

Expanded polystyrene foam can be used for the formation of articles of manufacture. For example, expanded polystyrene foam can be used for the formation of insulation.

The present invention also contemplates flame retarded expanded polystyrene foams containing flame retardant compounds having a solubility in styrene of about 0.5% to about 8% by weight at 25 ° C.

According to another aspect of the present invention there is provided a composition containing from about 0.5% to about 8% by weight of a flame retardant compound solubilized in styrene, wherein the compounds are as follows:

The present invention further contemplates a method for producing a flame retardant expanded polystyrene foam. The method includes forming a composition containing a flame retardant compound and a blowing agent solubilized in styrene and polymerizing styrene to form polystyrene beads, wherein the flame retardant compound is from about 0.5% to about 8% by weight at 25 ° C. It has a solubility in styrene of and has the following structure:

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The present invention further contemplates a process for producing molded flame retardant expanded polystyrene products. The method pre-expands unexpanded beads comprising polystyrene, a blowing agent, and a flame retardant compound having the structure: forming pre-expanded beads, optionally further expanding the beads to form a product. Wherein the beads are substantially free of antimony trioxide:

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The product may be a heat insulator.

Detailed description of the invention

The present invention relates generally to flame retardant expandable polystyrene foam compositions, flame retardant expanded polystyrene foams, methods of making such foams, and to products comprising the compositions and foams. According to one aspect of the invention, the flame retardant expandable polystyrene foam composition comprises a styrenic polymer such as polystyrene, and one or more flame retardant compounds. Optionally, the composition may comprise one or more synergists, stabilizers, or various other additives.

Flame retardant compounds of the invention are compounds having the following structure, tautomers, stereoisomers and polymorphs thereof (collectively referred to as "Compound (I)"):

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It has been found that the use of compound (I) to form flame retardant compositions results in thermally stable and effective expanded polystyrene foam. Unlike other compounds that interfere with foam formation, compound (I) is sufficiently soluble in styrene and does not adversely affect the formation of polystyrene foam.

The flame retardant compound has a solubility in styrene of about 0.5 to about 8 weight percent at about 25 ° C. In one aspect, the flame retardant compound has a solubility in styrene of about 3 to about 7 weight percent at about 25 ° C. In another aspect, the flame retardant compound has a solubility in styrene of about 4 to about 6 weight percent at about 25 ° C.

Moreover, the flame retardant compound has a solubility in styrene of about 0.5 to about 10% by weight at about 40 ° C. In one aspect, the flame retardant has a solubility in styrene of about 4 to about 8 weight percent at about 40 ° C. In another aspect, the flame retardant has a solubility in styrene of about 6 to about 8 weight percent at about 40 ° C.

The flame retardant compound is typically present in the composition in an amount of about 0.1 to about 10 weight percent of the composition. In one aspect, the flame retardant compound is present in an amount from about 0.3 to about 8 weight percent of the composition. In another aspect, the flame retardant compound is present in an amount of about 0.5 to about 7 weight percent of the composition. In another aspect, the flame retardant compound is present in an amount from about 0.7 to about 5 weight percent of the composition. In another aspect, the flame retardant compound is present in an amount of about 1 to about 2 weight percent of the composition. While various example ranges are given here, it will be understood that the exact amount of flame retardant compound used will depend upon the degree of flame retardancy desired, the specific polymer used, and the end use of the resulting product.

The expanded foam of the present invention is formed from vinyl aromatic monomers having the formula: for example styrene-based monomers:

H ₂ C = CR-Ar

Wherein R is hydrogen or an alkyl group having 1 to 4 carbon atoms, and Ar is an aromatic group having about 6 to about 10 carbon atoms (including various alkyl and halo-ring-substituted aromatic units). Examples of such monomers include styrene, alpha-methylstyrene, ortho-methylstyrene, meta-methylstyrene, para-methylstyrene, para-ethylstyrene, isopropenyl toluene, isopropenyl naphthalene, vinyl toluene, vinyl naphthalene, Vinyl biphenyl, vinyl anthracene, dimethylstyrene, t-butylstyrene, some chlorostyrenes (eg mono- and dichloro-modifiers), and some bromostyrenes (eg mono-, dibromo- and tribromo-modifiers) ), But is not limited to such.

According to one aspect of the invention, the monomer is styrene. Polystyrene is readily prepared by bulk or lump, solution, suspension or emulsion polymerization techniques known in the art. The polymerization can be carried out with free radical, cationic or anionic initiators such as di-t-butyl peroxide, azo-bis (isobutyronitrile), di-benzoyl peroxide, t-butyl perbenzoate, dicumyl peroxide, potassium Persulfate, aluminum trichloride, boron trifluoride, etherate complex, titanium tetrachloride, n-butyllithium, t-butyllithium, cumyl potassium, 1,3-tririthiocyclohexane, etc. . Further details regarding the polymerization of styrene alone or in the presence of one or more monomers copolymerizable with styrene are well known and are not described in detail here.

Polystyrene typically has a molecular weight of at least about 1,000. According to one aspect of the invention, the polystyrene has a molecular weight of at least about 50,000. According to another aspect of the invention, the polystyrene has a molecular weight of about 150,000 to about 500,000. However, it will be understood that if appropriate or desired, polystyrenes having a higher molecular weight can be used.

The flame retardant composition of the present invention may optionally comprise a synergist. The synergist may generally be present in an amount from about 0.01 to about 5 weight percent of the composition. In one aspect, the synergist is present in an amount from about 0.05 to about 3 weight percent of the composition. In another aspect, the synergist is present in an amount from about 0.1 to about 1 weight percent of the composition. In another aspect, the synergist is present in an amount from about 0.1 to about 0.5 weight percent of the composition. In another aspect, the synergist is present in an amount of about 0.2% by weight of the composition.

When a synergist is used, the ratio of the total amount of synergist to the total amount of flame retardant compounds is typically from about 1: 1 to about 1: 7. According to one aspect of the invention, the ratio of the total amount of synergist to the total amount of flame retardant compounds is from about 1: 2 to about 1: 4. Examples of synergists that may be suitable for use in accordance with the present invention include dicumyl, ferric oxide, zinc oxide, zinc borate, and oxides of group V elements such as bismuth, arsenic, phosphorus and antimony However, it is not limited thereto. According to one aspect of the invention, the synergist is dicumyl peroxide.

However, while the use of synergists has been described herein, it will be understood that no synergists are required to obtain effective flame retardant compositions. Thus, according to one aspect of the invention, the flame retardant composition is substantially free of synergists. According to another aspect of the present invention, the flame retardant composition is substantially free of antimony compounds. According to another aspect of the invention, the composition contains a synergist but is substantially free of antimony trioxide.

Flame retardant foams of the invention optionally comprise a heat stabilizer. Examples of heat stabilizers include zeolites; Hydrotalcite; Talc; Organotin stabilizers such as butyl tin, octyl tin, and methyl tin mercaptide, butyl tin carboxylate, octyl tin maleate, dibutyl tin maleate; Epoxy derivatives; Polymeric acrylic binders; Metal oxides such as ZnO, CaO and MgO; Mixed metal stabilizers such as zinc, calcium / zinc, magnesium / zinc, barium / zinc and barium / calcium / zinc stabilizers; Metal carboxylates such as zinc, calcium, barium stearate or other long chain carboxylates; Metal phosphates such as sodium, calcium, magnesium or zinc; Or any combination thereof, but is not limited thereto.

The heat stabilizer may generally be present in an amount from about 0.01 to about 10 weight percent of the flame retardant compound. In one aspect, the heat stabilizer is present in an amount from about 0.3 to about 10 weight percent of the flame retardant compound. In another aspect, the heat stabilizer is present in an amount from about 0.5 to about 5 weight percent of the flame retardant compound. In another aspect, the heat stabilizer is present in an amount from about 1 to about 5 weight percent of the flame retardant compound. In another aspect, the heat stabilizer is present in an amount of about 2% by weight of the flame retardant compound.

 Other additives that may be used in the compositions and foams of the present invention include, for example, extrusion aids (eg, barium stearate or calcium stearate), organoperoxide or dicumyl compounds and derivatives, dyes, pigments, fillers, Heat stabilizers, antioxidants, antistatic agents, reinforcing agents, metal scavengers or inactivators, impact modifiers, processing aids, mold releasing agents, lubricants, antiblocking agents, other flame retardants, other Heat stabilizers, antioxidants, UV stabilizers, plasticizers, flow aids, and similar materials. If desired, nucleating agents (eg, talc, calcium silicate or indigo) can be included in the polystyrene composition to control cell size.

The flame retardant compositions of the invention can be used to form flame retarded polystyrene foams, for example expandable polystyrene foams. Such foams can be used for a number of purposes, including but not limited to thermal insulation. Flame retardant polystyrene foams can be prepared by any suitable method known in the art. In general, the method includes either a "one step method" or a "two step method".

More commonly used "one-step processes" include dissolution of flame retardants in styrene followed by aqueous suspension polymerization carried out in two steps. The polymerization is carried out at about 9O < 0 > C for several hours, after which an initiator such as dibenzoyl peroxide accelerates the polymerization and then rises to about 13O < 0 > C, during which the blowing agent is added under high pressure. At this temperature, the dicumyl peroxide will complete the polymerization. A less commonly used “two step method” involves adding a flame retardant in subsequent steps with a blowing agent while raising to about 130 ° C. Typically pentane soluble flame retardants are used in the "two step process".

Further examples of methods that may be suitable for use in accordance with the present invention include, but are not limited to, US Pat. Nos. 2,681,321, each of which is incorporated herein by reference in its entirety; 2,744,291; 2,744,291; 2,779,062; 2,779,062; 2,787,809; 2,787,809; 2,950,261; 2,950,261; 3,013,894; 3,086,885; 3,501,426; 3,663,466; 3,663,466; 3,673,126; 3,673,126; 3,793,242; 3,793,242; 3,973,884; No. 4,459,373; No. 4,563,481; No. 4,990,539; 5,100,923; 5,100,923; And the methods provided in US Pat. No. 5,124,365. Procedures for converting expandable beads of styrene-based polymers into foamed moldings are described, for example, in US Pat. No. 3,674,387, each of which is incorporated herein by reference in its entirety; 3,736,082; 3,076,076; And 3,767,744.

Various foaming agents or blowing agents can be used to prepare the expanded or foamed flame retardant polymers of the present invention. Examples of suitable materials are provided in US Pat. No. 3,960,792, which is incorporated herein by reference in its entirety. Aliphatic hydrocarbons including, for example, ethane, ethylene, propane, propylene, butane, butylene, isobutane, pentane, neopentane, isopentane, hexane, heptane, and any mixtures thereof; Volatile hydrocarbons and / or halohydrocarbons such as methyl chloride, chlorofluoromethane, bromochlorodifluoromethane, 1,1,1-trifluoroethane, 1,1,1,2-tetrafluoro Ethane, dichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, trichlorofluoromethane, sym-tetrachlorodifluoroethane, 1,2,2-trichloro-1,1, 2-trifluoroethane, sym-dichlorotetrafluoroethane; Volatile tetraalkylsilanes such as tetramethylsilane, ethyltrimethylsilane, isopropyltrimethylsilane, and n-propyltrimethylsilane, and any mixtures thereof, are widely used for this purpose. One example of a fluorine-containing blowing agent is 1,1-difluoroethane provided under the trade name HFC-152a (FORMACEL Z-2, E.I. duPont de Nemours and Co.). Water-containing vegetable materials, such as finely divided corncobs, may also be used as blowing agents. As described in US Pat. No. 4,559,367, which is hereby incorporated by reference in its entirety, such plant material may also act as a filler. Carbon dioxide can also be used as blowing agent or as a component thereof. Methods of using carbon dioxide as a blowing agent include, for example, US Pat. No. 5,006,566, which is incorporated herein by reference in its entirety; 5,189,071; 5,189,071; 5,189,072; 5,189,072; And 5,380,767. Other examples of blowing agents and blowing agent mixtures include water with or without nitrogen, argon, or carbon dioxide. If desired, such blowing agents or mixtures of blowing agents can be mixed with ethers, hydrocarbons or alcohols with suitable volatility. See, for example, US Pat. No. 6,420,442, which is incorporated herein by reference in its entirety.

Expanded polystyrene foams may typically include various components and additives in the relative amounts described above with respect to the compositions used to form the foams. Thus, for example, expanded polystyrene foam according to the present invention may contain a flame retardant compound in an amount of about 0.1 to about 10% by weight of the foam. In one aspect, the flame retardant compound is present in an amount from about 0.3 to about 8 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount of about 0.5 to about 7 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount of about 0.7 to about 5 weight percent of the foam. In another aspect, the flame retardant compound is present in an amount from about 1 to about 2 weight percent of the foam. While specific ranges and amounts are described herein, it will be understood that other relative amounts of constituents in the foam are defined by the present invention.

The process for forming expanded polystyrene foam products, for example insulation, is as follows. The raw material resin used for manufacture of expanded polystyrene foam was obtained in the form of small beads having a diameter in the range of 0.5 to 1.3 mm. Small beads are manufactured and formulated to contain a small proportion of blowing agent by the manufacturer. The blowing agent was impregnated into the entire body of each small bead. The pre-expansion phase during manufacture is simply to expand the small beads to nearly 50 times their original size through heating and rapid gas release from the beads during its glass transition.

A predetermined amount of beads is introduced into the expansion equipment. The steam is introduced into the vessel and the stirrer mixes the expanding beads as the heat in the steam releases the pentane from the beads. The level indicator indicates when the desired specific volume is reached. After the pressure equalization phase, the expanded beads are released into a bed dryer and all condensed vapor moisture from the surface is dried. Pre-expansion is complete and another cycle is ready for operation. This process takes approximately 200 seconds to complete.

After the expanded beads have dried, they are blown into a large open storage bag for the aging process. Beads experienced a dynamic physical deformation in which the interior of the beads became a vacuum within the millions of cells produced. This vacuum should be equal to atmospheric pressure; Otherwise, this delicate balance will cause the beads to collapse or implosion. The maturing process of this expanded bead refills the beads to allow for equalization. This maturation can take 12 to 48 hours, depending on the expansion density of the desired beads. After aging is complete, the beads are then easy to form into blocks.

The molding process involves taking loosely expanded beads and forming the beads into solid blocks using a vacuum assisted, block mold. By utilizing a system of load cells, the computer can control the exact weight of the beads introduced into the mold cavity. Once the cavity is filled, the computer uses a vacuum system to remove residual air from the cavity. The vacuum is relaxed by live steam flowing over the entire bead mass in the cavity. This vacuum rinse process softens the polymer structure of the bead surface and immediately presses the mold cavity with live steam. The latent heat from the steam and subsequent pressure increase further expand the beads. Since this is a closed environment, the only way beads can expand is to fill any space between them so that the soft surfaces fuse together into a polyhedral solid structure. The computer releases pressure after reaching a predetermined set point. Loose beads are now fused into solid blocks.

Thermal curing is the next step in the process. This facilitates the curing process of freshly formed blocks, ensures that the material is dimensionally stable, and provides the best fabrication results for the completely dry material.

The invention is further illustrated by the following examples which should not be construed as limiting the scope of the invention in any way. Rather, it will be apparent that after reading the disclosure herein various other aspects, embodiments, modifications, and equivalents thereof may be used which may be suggested to one skilled in the art without departing from the spirit of the invention and the scope of the appended claims.

Example 1

N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide ("Compound (I)") was prepared according to the following exemplary procedure. Other procedures are known in the art and are not discussed herein.

900 g of xylene and 1 kg (6.57 mol) of tetrahydrophthalic anhydride (THPA, 95-96%) in a four-necked 5 L jacketed flask equipped with a nitrogen flow and water-cooled reflux condenser ). To the stirred (250 rpm) slurry, allylamine (413 g, 7.23 mol) was added via an addition funnel for 45 minutes. The reaction was exothermic and the temperature was maintained at 50-80 ° C. using a circulating bath fluid fixed at 30 ° C. After the allylamine addition was completed, the bath temperature was raised to 165 ° C. and maintained for 2 hours (complete reaction by GC). The circulation bath fluid temperature was reduced to 150 ° C. and the solvent was removed using a vacuum inhaler (˜3 ”Hg; Rxn T = 138 to 140 ° C.). After most of the xylene was removed, the bath temperature was reduced to 65 ° C. (Rxn T = 56 ° C.) and 500 g of BCM (bromochloromethane) were added followed by washing with a base detergent, aqueous solution (1,260 g of water, 50 g of Na ₂ CO ₃ ) was added and after stirring, The dark red / brown organic phase (1907 g: ˜500 g BCM, ˜1256 g product (65.8 wt.%), ˜200 g xylene) was separated from the orange aqueous phase (1,332 g). The analysis showed ˜100 area% product after finishing the caustic reaction.

N-allyl-tetrahydrophthalimide:

Into a four neck 5 L jacketed flask equipped with a nitrogen flow, about 500 g of BCM, about 20 g of aqueous HBr, about 20 g of ethanol were charged and the circulation bath temperature was about 2 to 3 ° C. (reaction T = 5 ° C., Initial stage). In a stirred (300 rpm) solvent, about 2,209 g (13.8 mol, 2.1 to 2.2 eq) of bromine solution and THPAI (1,907 g) of BCM / xylene solution were added from the opposite side of the flask through an addition funnel for about 2.5 hours. Fed together over the surface. Reaction temperature was made into less than 33 degreeC. The solution is stirred for an additional 30 minutes and an aqueous solution of water (1450 g), Na ₂ SO ₃ (20 g, 0.16 mol, FW = 126), Na ₂ CO ₃ (90 g, 0.85 mol, FW = 106) Added and the organic phase was washed (aqueous phase pH = 8-9). Methanol (1.7 kg) was added to the reactor at 45 ° C and the reaction temperature was raised to about 50 ° C (crude T is about 68 ° C). Another 1 kg of methanol was added while cooling the reactor to room temperature. The powder was filtered, rinsed with methanol and then dried at about 65 ° C. in an air circulation oven for about 2.5 hours to give 2625 g of white powder product (76% yield). Mp 104-118 ° C.

Brominated N-allyl-tetrahydrophthalimide (62.6 wt.% Br):

Example 2

To illustrate flame retardant efficacy, various compositions containing N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide ("Compound (I)") are prepared, which are usually Applied to ASTM Standard Test Method D 2863-87, referred to as Limit Oxygen Index (LOI) test. In this test, the higher the LOI value, the greater the flame retardancy of the composition.

A concentrate (10 wt% compound I) was formed, and then at a ratio of about 35 wt% concentrate to about 65 wt% PS-168 neat resin, the concentrate was placed in pure resin and injected via carbon dioxide Sample A was prepared by extruding low density foam. PS-168 is a versatile non-flame retarded grade of non-reinforced crystalline polystyrene sold by Dow Chemical Company. Its weight average molecular weight is about 172,000 Daltons, and the number average molecular weight is about 110,000 Daltons (measured by GPC). Molecular weight analysis was determined in THF using a Waters 150-CV modular gel permeation chromatography with differential refractometer and Precision Detectors model PD-2000 light scattering intensity detector and Ultrastyragel columns with porosities of 100, 103, 104 and 500 angstroms. The polystyrene standard (Showa denko) was used for the measurement of molecular weight.

The concentrate comprises about 10% by weight of compound I, about 0.5% by weight of hydrotalcite heat stabilizer, about 4.3% by weight of Mistron Vapor Talc, about 1.5% by weight of calcium stearate, and about 83.7% by weight of Dow PS-168 was contained. The concentrate was prepared on a Werner & Phleiderer ZSK-30 co-rotating twin screw extruder at a melt temperature of about 175 ° C. A standard dispersed mixing screw profile was used at a feed rate of about 250 rpm and about 1 kg / hour. The PS-168 resin concentrate was fed through a single screw gravimetric feeder, premixed powder additives and fed using a twin screw powder feeder.

The concentrate was then mixed into pure Dow polystyrene PS-168 using the same twin screw extruder, at a ratio of about 35% by weight of the concentrate to about 65% by weight of polystyrene, to prepare a foam using the following conditions: 1 Zone temperature (about 175 ° C.), zone 2 temperature (about 160 ° C.), zone 3 temperature (about 1300 ° C.) and zone 4 temperature (about 1300 ° C.), die temperature of about 145 ° C., screw speed of about 60 rpm, about Feed rate of 3.2 kg / hour, screen pack of 40/80/150, carbon dioxide pressure of about 290 to about 310 psig, melting temperature of about 160 ° C., torque of about 63 to about 70%, and about 2 to about Takeoff speed of about 3 ft / min.

The foam contained about 1.5 wt% talc and about 3.5 wt% flame retardant (about 2.2 wt% bromine) as the nucleating agent for the foaming process. DHT4A hydrotalcite was also used in an amount of about 5% by weight of the flame retardant compound to stabilize the flame retardant during the extrusion and foam-forming process. The foam was made using a standard two-hole stranding die (hole 1/8 inch in diameter) with one hole blocked. The resulting foam rod, 5/8 inch in diameter, had a very thin skin (up to 0.005 inches) and a fine closed cell structure. Carbon dioxide gas was injected into barrel # 8 (ZSK-30 is a 9-barrel extruder). The rod was foamed with carbon dioxide at a density of about 9.0 lbs / ft ³ (specific gravity of 0.14).

Control sample K was prepared as sample A except that the concentrate contained about 9% by weight of SAYTEX® HP900SG stabilized hexabromocyclododecane (HBCD).

The evaluation results are shown in Table 1 below.

The results indicate that N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide is a high potency flame retardant comparable to commercial HBCD.

Example 3

The thermal stability of N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide ("Compound (I)") used according to the invention was evaluated using a thermal HBR measurement test.

First, about 0.5 to about 1.0 g of a flame retardant sample was weighed and placed in a three neck 50 mL round bottom flask. Teflon tubing was then attached to one of the openings in the flask. Nitrogen was fed into the flask through a Teflon tube at a flow rate of about 0.5 SCFH. A small reflux condenser was attached to another opening on the flask. The third opening was closed. About 50% by volume glycol solution in water was flowed through the reflux condenser at a temperature of about 85 ° C. Viton tubing was attached to the top of the condenser and to a gas scrubbing bottle. Another two vessels were attached in series to the first vessel. All three vessels contained about 90 mL of about 0.1 N NaOH solution. After assembling the device, nitrogen was purged through the system for about 2 minutes. The round bottom flask was then placed in an oil bath at about 22O <0> C and the sample was heated for about 15 minutes. The flask was then removed from the oil bath and purged with nitrogen for about 2 minutes. The contents of three gas cleaning vessels were transferred to a 600 mL beaker. The vessel and the viton tube were rinsed into the beaker. The contents were then acidified with about 1: 1 HNO ₃ and titrated with about 0.01 N AgNO ₃ . The sample was run twice and the average of the two measurements was recorded. Lower thermal HBr values are preferred for heat stable flame retardants in extruded polystyrene foam or extruded polystyrene foam.

Sample B of the present invention was prepared as described in Example 1.

The evaluation results are shown in Table 2 below.

The results of the evaluation indicate that the flame retardant described herein is thermally stable, which does not decompose to release excessively heat-cut HBr when heated to typical operating temperatures used in extruded polystyrene foam.

Example 4

BN-451 (N,N'-에틸렌비스(5,6-디브로모-2,3-노르보르난디카르복시미드; CAS No. 52907-07-0) ("BN-451") 로부터 샘플 P 를 제조하였다. V-2 폴리프로필렌에서 낮은 로딩 (약 4 중량%) 으로 사용하기에는 주로 BN-451 이 권고된다. BN-451 의 스티렌 용해도는 약 25℃ 에서 약 0.1 중량% 미만이다.The effect of flame retardant solubility on the expandable polystyrene foam production performance was measured. SAYTEX

Sample P was taken from BN-451 (N, N'-ethylenebis (5,6-dibromo-2,3-norbornanedicarboxymid; CAS No. 52907-07-0) ("BN-451") BN-451 is mainly recommended for use with low loadings (about 4 weight percent) in V-2 polypropylene The styrene solubility of BN-451 is less than about 0.1 weight percent at about 25 ° C.

BN-451, 및 약 0.64 g 의 디벤조일 퍼옥시드 (물 중 약 75 중량%) 를 함유하는 혼합물을 제조하였다. 상기 후자의 혼합물에서는 불용성 BN-451 입자가 뚜렷이 보였으며, 상기 혼합물을 PVA 수용액을 함유하는 용기 내로 부었다. 상기 액체를, 반응기 내에서 전단응력을 생성하기 위한 배플 (baffle) 의 존재 하에 약 1000 rpm 으로 고정된 임펠러 형 교반기로 혼합하였다. 이어서, 혼합물을 하기의 가열 프로파일에 적용하였다: 약 2O℃ 에서 약 9O℃ 까지 약 45 분 내 가열 및 약 9O℃ 에서 약 4.25 시간 유지 (제 1 단계 조작).Aqueous suspension polymerization of styrene to form expandable polystyrene beads was carried out as follows. About 0.28 g of polyvinyl alcohol (PVA) in 200 g of deionized water was poured into a 1 liter Buchi glass tube. Separately, about 2.10 g of SAYTEX in about 200 g of styrene

A mixture containing BN-451, and about 0.64 g of dibenzoyl peroxide (about 75% by weight in water) was prepared. In the latter mixture, insoluble BN-451 particles were clearly seen, and the mixture was poured into a vessel containing PVA aqueous solution. The liquid was mixed with an impeller-type stirrer fixed at about 1000 rpm in the presence of a baffle for generating shear stress in the reactor. The mixture was then subjected to the following heating profile: heating from about 20 ° C. to about 90 ° C. in about 45 minutes and holding at about 4.25 hours at about 100 ° C. (first step operation).

No second step of the reaction (heating from about 90 ° C. to about 1300 ° C. in about 1 hour and holding at about 13 ° C. for about 2 hours) was not attempted. Typically, after about 2 hours, very small beads begin to form when stable suspension polymerization occurs. Failure of aqueous suspension polymerization was observed within about 2 hours at about 90 ° C. during the first step, evidenced by the rapid increase in viscosity and the formation of large polystyrene mass. Thus, the procedure was stopped after heating at about 90 ° C. for about 2 hours. These evaluation results indicate that compositions of this composition cannot be used to form refractory polystyrene beads. There is a need for flame retardants with higher styrene solubility.

These results demonstrate that flame retardants recommended for use in thermoplastic resins such as polypropylene and high impact polystyrene (HIPS) may not necessarily be correlated with their function in polystyrene foam such as expanded polystyrene.

Surprisingly, the inventors have found that N, 2-3-dibromopropyl-4,5-dibromohexahydrophthalimide ("Compound (I)") has the solubility necessary for effective use in expanded polystyrene processes. I found that. Solubility in styrene is about 8% by weight at about 25 ° C and about 10% by weight with moderate heat (about 40 ° C).

Expandable polystyrene beads were prepared as follows. About 0.28 g of polyvinyl alcohol (PVA) in about 200 g of deionized water was poured into a 1 liter vichy glass tube. Separately, a solution was formed containing about 1.68 g of FR, about 0.22 g of dicumyl peroxide, and about 0.64 g of dibenzoyl peroxide (about 75% by weight in water) in about 200 g of styrene. The latter solution was poured into a container containing an aqueous PVA solution. The liquid was mixed using an impeller type stirrer fixed at about 1000 rpm in the presence of a baffle for generating shear stress in the reactor. The mixture was then subjected to the following heating profiles: heating from about 20 ° C. to about 9O ° C. in about 45 minutes and holding about 4.25 hours at about 100 ° C. (first step operation); Heating from about 90 ° C. to about 13 ° C. in about 1 hour and holding at about 130 ° C. for about 2 hours (second step operation); And heating from about 13 ° C. to about 20 ° C. in 1 hour.

At the end of the first step, the reactor was pressurized with nitrogen (about 2 bar). Once cooled, the reactor was emptied and the mixture filtered. The flame retardant beads formed in the process were dried at about 60 ° C. overnight and then sieved to determine the bead size distribution. In this procedure, the sieves were stacked in order from the largest sieve size at the top to the smallest sieve size at the bottom, with a catch pan below them. The sieves were vibrated at about 50% power setting for about 10 minutes and the sieves were individually weighed (subtracting the container weight of the sieve screen). Based on the total mass of the substance, the weight percent of the substance at each sieve size was calculated. Approximately 88.4% conversion took place.

Sample P was described in Example 4. Sample V was similarly prepared without the addition of flame retardant compounds. The results are shown in Table 5.

These evaluation results indicate that the compositions of the present invention can be successfully used for the formation of flame retardant expandable polystyrene beads that can then be used for the formation of expanded polystyrene foam.

The foregoing has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise examples or embodiments disclosed. Obvious modifications or variations are possible in light of the above teaching. The embodiment (s) discussed are selected and provided to provide a best illustration of the principles of the invention and its practical application, so that those skilled in the art can make various changes and adapt the invention to the specific use contemplated. Described. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the scope fairly and lawfully given.

Although the following claims refer to materials, components, and / or components as present tense ("comprises", "is", etc.), such references are first contacted, blended or It refers to all materials, components or components according to the present specification as they existed at the time just prior to mixing or as present if they were not formed in solution if they were formed in solution. If performed in accordance with the present specification, it does not matter that a substance, component or ingredient may lose its original identity through modification or chemical reaction during the contacting, blending, mixing or in situ formation process.

Claims (14)

Flame retardant expanded polystyrene foam containing a flame retardant compound having the structure:

. The expanded polystyrene foam according to claim 1, wherein the flame retardant compound is present in an amount of 0.1 to 10% by weight of the foam. The expanded polystyrene foam according to claim 1, wherein the flame retardant compound is present in an amount of 0.5 to 7% by weight of the foam. The expanded polystyrene foam according to claim 1, wherein the flame retardant compound is present in an amount of 0.7 to 5% by weight of the foam. The expanded polystyrene foam according to claim 1, wherein the flame retardant compound is present in an amount of 1 to 2% by weight of the foam. The expanded polystyrene foam according to claim 1, wherein the flame retardant compound has a solubility in styrene of 0.5% to 8% by weight at 25 ° C. The expanded polystyrene foam of claim 1 wherein the flame retardant has a solubility in styrene of 0.5% to 10% by weight at 40 ° C. The expanded polystyrene foam of claim 1, wherein the expanded polystyrene foam is provided as an article of manufacture. 9. The expanded polystyrene foam of claim 8, wherein the article of manufacture is a heat insulator. delete A composition containing from 0.5% to 8% by weight of a flame retardant compound solubilized in styrene, wherein the compound has the structure

. A method of making a flame retardant expanded polystyrene foam, comprising: Forming a composition comprising a flame retardant compound solubilized in styrene and a blowing agent, wherein the flame retardant compound has a solubility in styrene of 0.5% to 8% by weight at 25 ° C. and has the following structure:

; Polymerizing the styrene to form polystyrene beads. A method of making a molded flame retardant expanded polystyrene product, comprising: Pre-expanding unexpanded beads comprising polystyrene, a blowing agent, and a flame retardant compound having the structure: wherein said beads are substantially free of antimony trioxide:

And Pre-expanded beads are molded, optionally further expanding the beads to form the product. The method of claim 13, wherein the product is a heat insulator.